This a great example of an important CXR sign. The large supraclavicular lymph node mass displaces the skin and subcutaneous tissues over the right clavicle, obliterating the gas/skin interface. This parallel companion shadow is seen clearly on the left side.

US-guided supraclavicular lymph node biospy report extract:

" Consistent with metastatic adenocarcinoma of lung primary.
Moderate to poorly differentiated carcinoma with small nests and marked clear cell changes.
Immunohistochemical studies:
TTF1 +
CK7 +
Napsin A +
CK20 -
CDX2 -
GATA3 -
SOX10 -."